Conductivity-Based Detergent Dosing Control for Rinse Stage Detection
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Solution Overview
Problem
Existing dosing systems for dishwashers and textile washing machines rely primarily on temperature sensors to control dosing cycles, which is impractical and less sensitive, especially in low-temperature cycles and those without renewed heating, limiting their effectiveness in modern detergents and rinse aids.
Innovation Solution
The method utilizes conductivity sensors to determine the concentration of electrolytes in the cleaning liquid, evaluating conductivity gradients to differentiate between wash cycles, making the dosing system independent of temperature conditions and ensuring accurate dosing without manual intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are used to control dosing cycles, then the dosing system can operate with simple sensor implementation, but the sensitivity and practicality of dosing control deteriorates, especially in low-temperature cycles
Solution Approach 1:
The patent replaces temperature-based control (thermal field) with conductivity-based control (electrical field). The conductivity sensor detects electrolyte concentration changes in the cleaning liquid, which correspond to different wash cycles and dosing requirements. This substitution provides higher sensitivity and reliability for dosing control, especially in low-temperature cycles where temperature-based detection becomes impractical.
Solution Approach 2:
The patent changes the control parameter from temperature to conductivity. By monitoring the conductivity of the cleaning liquid, the system can accurately detect different wash cycles (pre-rinse, main wash, rinse) and trigger appropriate dosing actions. Conductivity measurements provide more reliable and sensitive detection across all temperature conditions compared to temperature-based control.
2Reliability
If conductivity sensors are used to detect water changes and control dosing, then dosing accuracy improves across various wash cycles, but the device complexity increases due to additional sensor integration
Solution Approach 1:
The conductivity sensor serves multiple functions: detecting water presence, identifying different wash cycles through conductivity gradient analysis, and triggering dosing decisions. This multi-functionality reduces the need for multiple separate sensors and improves overall system reliability while managing complexity through functional consolidation.
Solution Approach 2:
The system continuously monitors conductivity values and compares them against threshold ranges to determine the current wash cycle stage. This feedback mechanism enables accurate, real-time dosing control based on actual liquid conditions rather than predetermined timing, significantly improving dosing reliability and adaptability to varying wash conditions.
3Adaptability or versatility
If temperature-based control is used, then the system works adequately in high-temperature cycles, but it becomes impractical and less sensitive in low-temperature cleaning cycles with reduced water consumption
Solution Approach 1:
The patent replaces temperature-based detection with conductivity-based detection, enabling the system to accurately control dosing in low-temperature cycles. Conductivity measurements are not affected by temperature limitations and provide consistent sensitivity across all operating conditions, including eco-friendly low-temperature and low-water-consumption cycles.
Solution Approach 2:
By changing from temperature parameter to conductivity parameter, the system gains adaptability to low-temperature operations. Conductivity-based control maintains high measurement precision and sensitivity regardless of temperature, allowing accurate dosing control in modern energy-efficient washing cycles that operate at reduced temperatures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the sensitivity and practicality of dosing control, allowing for precise dosing of detergents and rinse aids across various wash cycles, including those at lower temperatures, and ensures accurate detection of water changes, reducing errors and manual dosing needs.
Implementation Method 1
the conductivity sensor (18) has two contacts which are open to the environment and are preferably designed as contact pins protruding downwards from the bottom
Implementation Method 2
the sequence of determined conductivity values L is evaluated by the control unit (8) with regard to the profile of the absolute value of the conductivity and with regard to the gradient of the profile dL/dt of the conductivity
Data Source
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AI summary
The invention relates to a method for controlling a dosing appliance (5) of a stand-alone dosing system for a flowable detergent or washing agent, preferably for using in a dishwasher machine. Said dosing system (4) consists of a dosing appliance (5) and a container for at least one washing agent, that is embodied as a cartridge (11). Said dosing appliance (5) comprises a housing (6), at least one energy source (7) arranged inside the housing, at least one actuator (16) for carrying out the dosing, and an electronic control unit (8) for controlling at least the actuator (16). A conductivity sensor (8) connected to the control unit (8) in a circuit and open to the surroundings of the dosing appliance (5) is arranged on the housing (6). The method for such a dosing appliance (5) is carried out in such a way that, during the running of a washing cycle comprising at least two different rinsing stages (S1, S2), the conductivity measuring value (L) respectively instantaneously determined by the conductivity sensor (18) is continuously or discontinuously assessed by the control unit (8); the sequence of determined conductivity measuring values (L) is evaluated by the control unit (8) in terms of the course of the absolute value of the conductivity (L) and in terms of the gradient of the course (dL/dt) of the conductivity; and then, if the instantaneously measured conductivity measuring value (L) exceeds a maximum conductivity measuring value (Lmax) determined in the first rinsing phase (S1), and the gradient of the course (dL/dt) of the conductivity measuring value exceeds a certain threshold value (D), this is evaluated by the control unit (8) as being a water renewal and beginning of the next rinsing stage (S2).